MEASUREMENT RESULTS OF FLUID FORCE ACTING ON ARMOR BLOCKS OF THE BACK SLOPE OF THE RIVER LEVEE WHEN OVERFLOWING

Abstract

 One of the levee strengthening construction methods that the Ministry of Land, Infrastructure, Transport and Tourism is studying is the surface protected type, which is a construction method that protects the surface of the levee body with a covering material. On the back slope of the embankment, the structure is protected with an erosion prevention sheets, a block, etc., but in order to study the stability of the block, the flow on the back slope at the time of overflow is an supercritical flow, and there is a problem that it is difficult to evaluate the fluid force acting on the block.Therefore, in this study, we changed the shape of the surface protrusion of the block using a small-scale model and measured the fluid force acting on the block by overflow water. As a result, it was confirmed that by providing an inclination in the surface protrusion or reducing the protrusion height, the drag acting on the block is reduced, but the lift force is conversely increased. In addition, using the coefficient obtained from the conventional hydraulic property test, it was shown that the fluid force acting on the block can be larger than the fluid force obtained from the calculation formula of the mechanical design method of the river revetment.